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TWO-DIGIT MULTIPLICATION—USING AN ARRAY MODEL

Grades: 3‒4

Students use an array model to find products of two-digit multiplication problems up to 50 × 50. Students split arrays into as many as four smaller arrays that represent “friendly” facts—facts whose products they already know. Students then add the partial products to find the product of the original multiplication problem. 

OBJECTIVES 
  • Students will use a rectangular array model to explore two-digit multiplication problems up to 20 × 20.
  • Students will see the relationship between a multiplication problem represented in numerical form and the same problem represented with an array.  
  • Students will develop and use strategies for splitting a rectangular array into smaller arrays in which the partial products are easier to calculate mentally.
COMMON CORE CONNECTIONS 
Mathematical Practices

(1) Make sense of problems and persevere in solving them; (2) Reason abstractly and quantitatively; (3) Construct viable arguments and critique the reasoning of others; (5) Use appropriate tools strategically; (7) Look for and make use of structure.

Content Standards

3.OA5; 4.NBT5

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This activity is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License: http://creativecommons.org/licenses/by-nc-sa/3.0/. If you adapt and/or share this activity, you must attribute it to "KCP Technologies, a McGraw-Hill Education Company." You may distribute it only non-commercially under the same or similar license.


This material is based upon work supported by the National Science Foundation under KCP Technologies Award ID 0918733, with grant period September 1, 2009 through August 31, 2013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
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